THE TRANSMISSION GALLERY
|Photos by Dan Glover||Page last updated: 2017-05-22|
|When the BBC and commercial DAB networks were developed, Wrotham was conspicuous by its absence from the list of sites. |
I had previously assumed this was due to frequency clearance issues with Europe - and indeed the installation carries the London multiplexes rather than Kent and has maximum ERP to the north west.
DAB transmissions from the nearby sites at Kemsing and Otford have ceased now that Wrotham is operational. (In the case of Otford, the DAB antenna has been removed.)
|Some years ago I used to have access to Wrotham as a "site sharer" (in connection with an amateur radio repeater - long since re-located). Security has been strengthened significantly in recent years.|
|The DAB antenna consists of fourteen dipoles (configured as two arrays of seven) which are mounted along one edge of the Band II array.|
The Ofcom data is slightly inconsistent with the planning documents but it seems likely that both halves are normally used, shared by all services.
The spacing of the dipoles is clearly irregular - presumably for null-filling or beam-tilting purposes.
|As well as the national services, Wrotham is used to transmit BBC Radio Kent and KMFM. BBC Kent is transmitted from an array of six band II log periodics at the very top. A slant-polarised group of four, point east, which is the direction of maximum ERP. A single slant-polarised aerial points south-southwest (left), and a single horizontally-polarised aerial points north-northeast (right). KMFM uses the slant-polarised phased dipoles to the left, on bearing 160. There's a similar pair of dipoles below the main Band II array.|
|Also of interest in this photo are a steerable SHF link (not far below the work platform), which was used for BBC News OB links at 2.6 GHz, and what appears to be a group of UHF logs (bottom of image).|
Kemsing | Otford
Planning Application 10/01714/FL at Tonbridge & Malling Council
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